1. Field of the Invention
This invention relates to mass dampers for reducing undesirable vibration in automobiles having an airbag mounted in a steering wheel. More particularly, the present invention provides a simplified and improved resilient attachment capable of reducing assembly variances, thereby improving performance and customer satisfaction.
2. Disclosure Information
It is well known in the automotive noise, vibration and harshness art to use mass dampers to reduce or suppress vibration of specific components within an automotive vehicle. U.S. Pat. No. 5,024,464 generally discloses the use of an airbag unit, or a portion thereof, as a mass damper for suppressing the vibrations of the steering wheel. In each of the embodiments shown, the airbag unit is attached to the steering wheel by a rigid fastener disposed axially through a resilient bushing. Fasteners such as those disclosed produce a clamping force to the bushing. This clamping force preloads the bushing, which effects the rate of the bushing, and therefore the resonant frequency of the mass damper system. Since the airbag (as the mass) and bushings (as the spring) are tuned to a predetermined frequency to cancel objectionable motion of the steering wheel, variations in the rate of the bushing are undesirable. Either too little or too much clamping force will reduce the efficiency of the mass damper by moving its resonant frequency away from the predetermined frequency. Therefore, the clamping force applied to the bushing must be controlled during the assembly of the airbag to the steering wheel. Additionally, as a field serviceable fastener, it is not possible to ensure the application of the correct clamping force when serviced by personnel not having the proper tools.
It would be desirable to have a mass damper system using an airbag unit, or a portion thereof, resiliently attached to a steering wheel in a simple and repeatable manner so as to ensure efficient damping of vibrations, both after assembly and after service in the field.